Improved management of infection in patients with sickle cell disease has led to their increasing longevity and to the emergence of chronic renal insufficiency as a major cause of morbidity and mortality. Sickle cell patients with renal insufficiency have a median survival of 27 years as compared to 51 years for sickle cell patients with normal renal function. The etiology of renal insufficiency in these patients is unknown, but given its poor prognosis, early detection is an important prerequisite to the development of successful therapies. Several questions remain unanswered: 1) What is the pathogenesis of the hyperfiltration and the elevated renal blood flow seen in young sickle cell patients? 2) Who among these patients is at greatest risk of developing renal function? 3) What is the pattern of progression of renal insufficiency in these patients and how can it be prevented? This cross-sectional descriptive project is designed to obtain preliminary data leading to a larger study of renal function and hemodynamics in patients with sickle cell disease.